a. Technical Field
The instant disclosure relates to electrical impedance-based contact sensing, including contact between tissue and electrodes disposed in or on a medical device.
b. Background Art
Catheters are used for an ever-growing number of procedures. For example, catheters are used for diagnostic, therapeutic, and ablative procedures, to name just a few examples. Typically, the catheter is manipulated through the patient's vasculature and to the intended site such as, for example, a site within the patient's heart. The catheter typically carries one or more electrodes, which may be used for ablation, diagnosis, and the like.
In many procedures, it may be beneficial to know the contact status of an electrode (e.g., in contact with tissue, in a blood pool) on a catheter. For example, in an electrophysiology mapping procedure, the electrical signal present on an electrode may vary depending on whether the electrode is in contact with tissue, or adjacent to the tissue in a blood pool, and that difference may be accounted for in software. In another example, in an ablation procedure, it may be desirable to only drive an ablation current when an electrode is in contact with the tissue to be ablated.
One existing methodology that may be used to determine whether an electrode on a catheter is in contact with tissue includes driving a current between the electrode and an electrode elsewhere within the patient (e.g., at a stable position within the patient) or on the exterior of the patient (e.g., on the patient's skin) and assessing the impedance between the electrodes. To determine an impedance between those electrodes, the electric potential of the electrode on the medical device may be referenced to a third electrode, which may also be elsewhere within the patient or on the exterior of the patient.
The foregoing discussion is intended only to illustrate the present field and should not be taken as a disavowal of claim scope.